Digitizing Audio from Film using Wordclock as a reference

When transferring audio it is important for the audio to run at the correct speed, positional lock with the moving image a separate procedure often using a punch frame or clapper at the beginning of the reel . If the speed is not correct the sound and image will drift apart, the longer the reel the further they can drift.

We were asked to devise  system to make a simple locked transfer from film to Digital Audio, the customer also wanted to control the film from the DAW. We recommended  our BS-1 Bi phase generator with Sony 9 pin control input. To simplify the system added  a wordclock reference input to the BS-1 removing the need to a video sync generator.

If the workstation does not have a Sony 9 pin output but has Midi Machine Control then our P2MMC-usb can be used to control the BS-1.

Protools Loops, LTC Dropout and Master Error (RM-6/SR)

This week I have added yet another menu to the software as follows!

Menu 022- Rdr Dropout/Master Code Jump
0= Ignore 1=10frm Dropout 2=Re-Lock

The default selection in the original software is equivalent to 1=10frm Dropout.

Protools Loops
When you loop on Protools as a master the slave machines did not follow as the standard setting will roll over timecode jumps, Select 2=Re-Lock for the slaves to follow.

LTC Dropout
For Live performance I have been asked to make the system Jam to the LTC and then ignore dropouts. Select 0=Ignore for this. Once the system has seen timecode the generator will run as master until either
1) The Reader receives Stationary timecode
2) The unit receives a stop command.

Master Error
The software now displays a master error (the difference between the generator and the master timecode) in the same way as the slaves. The master error is only displayed when not zero. If not zero and changing then the the master and controller are not locked to the same reference.

 

VDCP - Video Disk Control Protocol

With the onset of file based systems I am surprised that I have not been asked before to implement this protocol. A few years ago we added the DD35 protocol to the SR-4 for FranceTelevision to control a EVS Video Server using . We have also implemented some Odetics support. The DD35 and  Odetics protocols  are both of these are extensions to the Sony P2  protocol as is our own xmc protocol used by CBServer. VDCP uses the same RS422 format and speed but has a completely different structure.

I have modified our Sony P2 test software to include the basic VDCP command set and we can now read the file names, select clips and control the transport, the next step will be Synchronisation and Insert Record.

There are still a few commands that I am having trouble with, but the basics are there. The first software will be for the the RM-6 synchroniser, I will then add the protocol to the UR controllers.

When will we implement Ethernet protocols? The problem is that no protocol stands out as a standard. Most are in house protocols which are not published, this makes them difficult if not impossible to implement.

No More Eproms!

The RomUpd card and program are now working very well, and all future SR-4's, RM-6's and dedicated systems  will have it fitted.  This week I was adding a user request to the software and used it for debugging the program. There is nothing like using a program to work out the wrinkles. The installation is also easy as only four connections are made to the processor board with NO track cuts. Just be careful not to lose the screws!

USB-422 Low Latency Driver for Mac

The USB-422 uses the FTDI chipset, this has been very reliable and has the advantage of well supported drivers for Windows, Mac and Linux.

The only drawback of the standard FTDI driver is that it is shipped with a standard latency of 16 mSec which is long for RS422 control, especially at 29.97fps where one frame is only 33 mSec.

The data sheet shipped with the USB-422 includes details of how to reduce the latency and change the com port number for Windows applications, I have just modified this to suggest a latency setting of 1 or 2 mSec and not 4 mSec as before.

Latency adjustment for the Mac is more complicated as the driver must be modified and re-installed. To make this modification easier I have updated the USB-422 web page with a low latency driver and installation instructions.

http://www.colinbroad.com/cbsoft/usb422/usb422.html
  

SR-4/RM-6 Field Programable Update

The SR-4 and RM-6 are both fully supported current products, at one point I was designing replacements but realised that then I would have to support both old and new. I decided to concentrate on supporting the current SR-4 and RM-6. For example they are both now supplied with bi-level and tri-level video sync inputs. The upgrade kit for this is available so that even the oldest of units can be modified.

The SR-4 and hence the RM-6 were designed in the days when EPROMS ruled, all my current products have field programable software and some even have field programable hardware! I finally worked out how add this feature to the SR-4 and RM-6. The new add on board plugs in in place of the EPROM and holds two versions of the software, the programming software (Available for both MAC and Windows)  to reprogram one at any time. The user can then select which version to use, in this way even if the new version is corrupted there is always a working version available.

We will be offering an upgrade kit  and all future units will be shipped with the modification.

Modification instructions will be available on the SR-4 and RM-6 web pages, CB Electronics and selected agents will offer an upgrade service.

Track Arming using Sony P2 Protocol

I am frequently asked "How many tracks is it possible to arm using Sony protocol?"

Using the Sony P2 protocol the maximum tracks that can be armed is 112 calculated as follows
Maximum number of data bytes = 15
One bute is used for analog audio, video and Insert or Assemble
14 bytes may be used for track arming 14*8 = 112

The track arm tally request command includes a byte with a byte specifying offset and length making it is possible to request more track arm tallies but this is not normally used.

Not all manufactures have implemented 112 tracks, within CB the RM-6 and SR-4 support 96 tracks, The UR-422 and UR-422usb support 64 tracks. CBServer currently supports 80 tracks which will soon be increased to 96 tracks. Until recently Pro-Tools supported a maximum of 48 Tracks.


When I originally designed the SR-4 8 or 16 record tracks per machine was standard (DA-88,DD-8...) I provided system track arming to cope with recording onto multiple machines by allowing each record key to be routed to any track on any machine.

With advances in computer hardware it is now common place to have a single record machine with 64 tracks and 96 or more are being discussed.

This question came up recently at Twickenham studios, the AMS-Neve DFC MCS supports a maximum of 48 tracks on each output port, paradoxically the DFC supports 96 track arms internally. To use all 96 tracks it is necessary to use two output ports.

To cope with the limited track arm capability of the DFC output ports CB have written software so that two  DFC-MCS ports are connected to two inputs on the X-4 software. An extra option has been added allowing  the track arming on une input to be offset by 48 tracks.